chernobyl, environmental effects, and the dichotomy ... - ocw · journal of animal ecology 4.6...
Post on 26-Jul-2020
4 Views
Preview:
TRANSCRIPT
Chernobyl, Environmental Effects, and the Dichotomy in Radioecology
Tom Hinton
Institute of Environmental Radioactivity
Fukushima University
26 April 1986
Contaminated 200,000 km2
350,000 people relocated
Radioactive releases for 10 days
CHERNOBYL
T. HInton, IER, Fukushima University
Extent of contaminant dispersal ?
Human mortality ?
Mutation rates ?
Long term effects ?
A hallmark of information about
Chernobyl (and now Fukushima) has
been CONTROVERSY….
T. HInton, IER, Fukushima University
In 2004 – 2006, the IAEA
established the
CHERNOBYL FORUM
Goal of reaching international
consensus and eliminating the
controversy
about the effects of the
Chernobyl accident
T. HInton, IER, Fukushima University
World Health Organization
International Atomic Energy Agency
United Nations Development Programme
Food and Agriculture Organization
United Nations Environment Programme
United Nations Scientific Committee on
the Effects of Atomic Radiation
United Nations Office for the
Coordination of Humanitarian Affairs
CHERNOBYL FORUM
The World Bank
Belarus
Russian Federation
Ukraine
plus an additional 80 experts
from 12 countries
T. HInton, IER, Fukushima University
• Before Chernobyl
• Chernobyl overview
• temporal aspects
• general effects to major classes of organisms
• indirect effects – confounding variables
• Possible reasons for controversy
T. HInton, IER, Fukushima University
Pre-Chernobyl…
• wealth of data about the
biological effects of
radiation on plants and
animals
• early data came from…
• laboratory exposures
• accidents (Kyshtym, 1957)
• areas of naturally high background
• nuclear weapons fallout
• large-scale field irradiators
T. HInton, IER, Fukushima University
Lethal Acute Dose Ranges(Whicker and Schultz, 1982)
Pre-Chernobyl…
T. HInton, IER, Fukushima University
• minor effects (chromosomal damage; changes in reproduction and
physiology)
Effects from Short Term Exposures (5 to 60 d)
Pre-Chernobyl…
• intermediate effects (selective mortality of individuals within a
population)
T. HInton, IER, Fukushima University
0.001 0.01 0.1 1 10 100 1000
Gy / d
x/10
DOSE (Gy) to DOSE RATE (Gy / d) CONVERSION
(5 to 60 d)
T. HInton, IER, Fukushima University
R. Alexakhin (RIARAE, Obninsk)
M. Balonov (IAEA, Vienna)
N. Gentner (UNSCEAR, Vienna)
J. Hendry (IAEA, Vienna)
T. Hinton (University of Georgia)
B. Prister (Kiev University)
P. Strand (NRPA, Oslo)
D. Woodhead (Centre for Environment, Fishery and Aquaculture, UK)
Effects of Radiation on the Environment:
Findings of the UN Chernobyl Forum
Within Chernobyl’s 30-km zone
0
20
40
60
80
100
0.1 1 10 100
months post accident
Rel
ati
ve
Co
ntr
ibu
tio
n
Do
se (
%)
I II III
• Environmental effects were specific to 3 distinct time periods
• Biota were exposed to a diverse group of radioisotopes
• Tremendous heterogeneity and variability (in all parameters)
• Accident occurred at a period of peak sensitivity for many biota
T. HInton, IER, Fukushima University
• Severe effects to biota
• High dose to thyroids
from iodine
First 20 to 30 days
0
20
40
60
80
100
0.1 1 10 100
months post accident
Rel
ati
ve
Co
ntr
ibu
tio
n
Do
se (
%)
I
• Gamma exposure dose rates were
> 20 Gy / d
• Dominated by short-lived isotopes99Mo; 132Te/I; 133Xe; 131I; 140Ba/La
T. HInton, IER, Fukushima University
100
COOLING POND
1 km
TOWN OF PRIPYAT
REACTOR1
10
100
100
1
0.1
RIVER PRIPYAT
20 Gy /d
2 Gy /d
0.02 Gy /d
0.2 Gy /d
(1 R / h ~ 0.2 Gy / d; UNSCEAR 2000)
Air Exposure Rates on 26 April 1986
T. HInton, IER, Fukushima University
0.001 0.01 0.1 1 10 100 1000
Gy / d
• Dose rates from gamma
exposures ranged from
0.02 to 20 Gy / d
T. HInton, IER, Fukushima University
0.001 0.01 0.1 1 10 100 1000
Gy / d
• Acute adverse effects within
10-km zone
• Mortality to most sensitive
plants and animals
• Reproductive impacts to
many species of biota
First Phase
T. HInton, IER, Fukushima University
Second Phase
0
20
40
60
80
100
0.1 1 10 100
months post accident
Rel
ati
ve
Co
ntr
ibu
tio
n
Do
se (
%)
II
• Decay of short-lived
isotopes
• Radionuclide migration
• β to δ ~ 6:1 to 30:1 with
> 90 % of dose from β
T. HInton, IER, Fukushima University
Third and Continuing Phase
0
20
40
60
80
100
0.1 1 10 100
months post accident
Rel
ativ
e C
ontr
ibu
tion
Dos
e (%
)
III
• Dose rates are chronic, < 1% of initial
• 137Cs and 90Sr dominate dose
• Beta to gamma contributions more comparable, depends
on bioaccumulation of Cs
• Indirect effects dominate
• Genetic effects persist; although some results are controversial
T. HInton, IER, Fukushima University
• Shift in ecosystem structure:
Deceased pine stands were
replaced by grasses, with a
slow invasion of hardwoods
• Genetic effects extended in time
1993, pines of 5 to 15 Gy had 8 X
greater cytogentic damage than
controls
General Effects to Plants
• Morphological mutations 1 to 15 Gy
(e.g. leaf gigantism)
• Hardwoods more radioresistant
• Evidence of adaptive responseT. HInton, IER, Fukushima University
Most radiosensitive species in Chernobyl zone: Scots pine (Pinus
sylvestris L.)
Typical morphological changes in Scots pine due to radiation:
cancelling apical dominance (deletion of the main trunk)
Normal development
Cancelling apical
dominance
V. YoschenkoT. HInton, IER, Fukushima University
Most radiosensitive species in Chernobyl zone: Scots pine (Pinus
sylvestris L.)
Typical morphological changes in Scots pine due to radiation:
cancelling apical dominance (deletion of the main trunk)
V. YoschenkoT. HInton, IER, Fukushima University
• Growth and developmental problems
Twisted
needles
0.001 0.01 0.1 1 10 100 1000
Gy / d
0.3 Gy / dGeneral Effects to Plants
• Inhibition of photosynthesis, transpiration
• Short term sterility
• Chromosome aberrations in meristem cells
• High mutation rates in wheat due to non-
targeted mechanisms
T. HInton, IER, Fukushima University
Arabidopsis
• research from 1987 to 1992
(Abramov, Shevchenko, et al).
• effect per unit dose was lower at
high-dose rate; low dose
chronic IR exerted a greater
effect per unit dose
• β contributed 82 to 96% of dose
• in 1992, mutations were still
4 to 8 times > than controls
T. HInton, IER, Fukushima University
General Effects to Rodents
• During Fall 1986, rodents population < 2- to 10-fold, dose rates
1 to 30 Gy/d (δ & β)
0.001 0.01 0.1 1 10 100 1000
Gy / d
• Dose-rate dependent increase in reciprocal translocations
• Increased mortality of embryos
• Numbers of mice recovered within 3 years (immigration),
but cytogenetic effects persisted
• At ~ 0.1 Gy/d temporary infertility, reduced testes mass
T. HInton, IER, Fukushima University
• ~ 30 to 40 generations post-accident
• lower dose rates
• chronic exposures
• inadequate dosimetry
• sample size and technique sensitivity
• indirect effects (immigration)
• interpretation of results from new
methods (microsatellites)
From virtually no effect….
… to significantly elevated mutation rates
Effects Data from Rodents
Collected in Phase III Are
Ambiguous and Controversial
0
20
40
60
80
100
0.1 1 10 100
months post accident
Rel
ativ
e C
ontr
ibu
tion
Dos
e (%
)III
T. HInton, IER, Fukushima University
• 60 to 90% of initial contamination captured by plant canopies
• Majority washed off to soil and litter within several weeks
• Populations of soil
invertebrates reduced
30-fold, reproduction
strongly impacted
General Effects to Soil Invertebrates
T. HInton, IER, Fukushima University
• 30 Gy altered community
structure (species
diversity) for 2.5 years
• Dose and effects to invertebrates
in forest litter were 3- to 10-
fold higher than those in
agricultural soils
General Effects to Soil Invertebrates
T. HInton, IER, Fukushima University
• Some suggestions of genomic instability (increase freq.
of cellular damage in offspring, while contamination decreased)
• Plant data suggest that chronic low-level irradiation might alter the
genetic structure of populations, increasing the karyotypic
variability in the offspring
• Evidence of DNA hypermethylation in plants: such epigenetic
modification is thought to be a defense strategy to reduce genome
instability
General Cytogenetic Effects
• Decline in cytogenetic damage lagged behind the
decline in radiation exposure
T. HInton, IER, Fukushima University
4 km N of Reactor
50,000 people
Pripyat
Abandoned
Indirect Effects of Human Abandonment
135,000 people and 35,000 cattle
evacuated
Dozens of towns and villages
deserted.
T. HInton, IER, Fukushima University
Przewalski Horses
Russian Boar
Wolves
With the removal of humans,
wildlife around Chernobyl are
flourishing
48 endangered species
listed in the international
Red Book of protected
animals and plants are
now thriving in the
Chernobyl Exclusion
Zone
T. HInton, IER, Fukushima University
ZONE DWELLERS
Reappeared: Lynx, eagle owl, great white egret,
nesting swans, and possibly a bear
Introduced: European bison,
Przewalski's horse
Booming mammals: Badger, beaver, boar, deer, elk, fox, hare,
otter, raccoon dog, wolf
Booming birds: Aquatic warbler, azure tit, black grouse,
black stork, crane, white-tailed eagle
T. HInton, IER, Fukushima University
Period 1 (first month)
Period 2 (1 to 12 months)
Period 3 (> 1 year)
Acute adverse effects within 30-km zone
Mortality of conifers; reproductive impacts
to plants & animals
Lowered dose rates
Morphological effects
Soil invertebrates impacted
Ongoing recovery
Secondary effects due to human abandonment
Noticeable positive impacts
Long term genetic consequences are unknown
BROAD SUMMARY
T. HInton, IER, Fukushima University
Main conclusions of the Chernobyl Forum
Radiation-induced effects on plants and animals
Irradiation caused numerous acute adverse effects on the plants and animals living up to 10-30 kilometres from the release point.
The following effects caused by radiation-induced cell death have been observed in biota:
Increased mortality of coniferous plants, soil invertebrates and mammals; and
Reproductive losses in plants and animals.
A few years were needed for recovery from major radiation-induced adverse effects in populations of plants and animals.
“Due to removal of human activities, the Exclusion Zone has paradoxically become a unique sanctuary for biodiversity.”
(Chernobyl Forum Report, 20066)
T. HInton, IER, Fukushima University
Wildlife defies Chernobyl
radiationBy Stephen Mulvey
BBC News
« It contains some of the
most contaminated land in
the world, yet it has become
a haven for wildlife - a nature
reserve in all but name. »
20 April 2006
Chernobyl 'not a
wildlife haven'
By Mark Kinver
Science and nature reporter
BBC News
« The idea that the exclusion
zone around the Chernobyl
nuclear power plant has
created a wildlife haven is not
scientifically justified, a study
says. »
14 August 2007
T. HInton, IER, Fukushima University
Dichotomy
Chernobyl
‘Shows Insect Decline'
By Victoria Gill,
Science Reporter, BBC NEWS
18 March 2009
“Two decades after the explosion at the Chernobyl nuclear
power plant, radiation is still causing a reduction in the numbers
of insects and spiders”.
T. HInton, IER, Fukushima University
Chernobyl
‘Shows Insect Decline'
By Victoria Gill,
Science Reporter, BBC NEWS
18 March 2009
“Two decades after the explosion at the Chernobyl nuclear
power plant, radiation is still causing a reduction in the numbers
of insects and spiders”.
A. Moller and T. Mousseau
T. HInton, IER, Fukushima University
T. HInton, IER, Fukushima University
0.001 0.01 0.1 1 10 100 1000
Gy / d
d
Gy
Gy
Gyx
d
hx
h
Gy0000024.0
10241.0
6
0.000001
IAEA
Guidelines
1 & 10 mGy / d
T. HInton, IER, Fukushima University
http://www.nature.com/articles/srep19974
Link to a poorly done study on cataracts in rodents, published in a
prestigious journal (be sure to read the comments section at the
end of the manuscript to learn why this is poor science)
The second link is an interesting write up by the BBC that
describes the dichotomy that exists in radioecology concerning
environmental effects and the role that Moller and Mousseau play
in furthering it
http://www.bbc.com/earth/story/20160421-the-chernobyl-exclusion-zone-is-arguably-a-nature-reserve
JOURNAL Impact Fact.
Nature 32.2
Science 31.4
Environmental Health Perspectives 6.2
Evolution 5.8
Journal of Applied Ecology 5.6
Ecological Applications 4.6
Journal of Animal Ecology 4.6
Heredity 4.2
Journal of Evolutionary Biology 4.0
Oecologia 3.9
Biology Letters 3.6
Behavioral Ecology 3.4
Microbial Ecology 3.4
Ecological Indicators 3.1
Journal of Ornithology 1.7
Cytology and Genetics 0.2
2015 15
2014 6
2013 9
2012 7
2011 8
2010 11
2009 4
2008 5
2007 6
84
Dichotomy is driven by the prolific publication of substandard data, generated by Moller and Mousseau, that are counter to established paradigms in RB and RE…
T. HInton, IER, Fukushima University
• Poor dosimetry can cause misinterpretation of data
• Spatial heterogeneity of exposure; free-ranging wildlife
• Confounding variables and indirect effects
• Questionable statistical analyses
• Lack of appropriate controls
• What constitutes a “significant effect”??
• Motives beyond science ??
Potential Causes for Controversial Data
T. HInton, IER, Fukushima University
Criticism of M&M is related to their:
• Poor experimental designs
• Questionable statistical analyses
• Bad methodologies
• Inadequate dosimetry
• Not accounting for confounding variables (e.g., humans)
T. HInton, IER, Fukushima University
The take home lessons relative to this dichotomy are:
Do not believe everything you read…..even if it is scientific material published in prestigious journals
Be critical of EVERYTHING you read….evaluate thoroughly!
Formulate your own conclusions,based on your scientific training
top related